Written for the magical reveal meme on LJ. Written for this prompt: "When Morgana comes to try and take over Camelot, Merlin won't let the city fall to her again so he goes all bamf!warlock on her- outing himself in the process" CanonAU.

This fic was written for the magical reveal meme! over on LJ. (If you google magical reveal meme, it'll come up - fanfic won't let me write the link).

PROMPT: When Morgana comes to try and take over Camelot, Merlin won't let the city fall to her again so he goes all bamf!warlock on her- outing himself in the process

Obviously, I own nothing.

When Arthur finally finds out, it's Gwaine's fault. (Actually, it's Morgana's fault, but Arthur has a tendency to see what he wants to see). The castle has been overrun, Arthur has been betrayed by yet another family member, and injured to boot, but it's nothing compared to how he feels when Merlin, frantically fussing around his wound, asks about the knights, about Gwaine.

"Sir Gwaine has been captured," Arthur grits out, and wishes he hasn't. Merlin's body goes stiff and tall, and his face slides into a mask that Arthur suppresses a flinch to look at.

"No."

The word is a short, sharp rebuff, and Arthur does flinch, but Merlin isn't looking at him. His eyes are fixed over the King's head, on the heavy wooden door barring them inside Gaius' chamber.

"Merlin!" Gaius' tone is a screaming warning, but Merlin merely shrugs him off as he advances toward the only barrier holding off Morgana's hoard.

"MERLIN!" Arthur is positive, positive, that Merlin has lost his mind, that the betrayal and the battle have taken some heavy toll, but when Merlin turns back to look at Gaius, all Arthur sees is ice-cold determination.

"This isn't happening, Gaius," he says, his voice steely calm, "I will not let her spend one single second on the throne of Camelot. I will not."

Arthur's head is reeling, from the loss of blood, from the adrenaline, from the pure, untouchable fear at the heart of all of it, but it stops when Merlin turns to him, eyes wide in his pale face. Something resembling grief flashes across the man's features, cutting so deep that Arthur briefly wonders if it's always been there, before he whispers, "I'm so sorry," and his eyes flash gold.

It's a while before Arthur manages to get to the Great Hall, running hard, sword in hand, trying not to notice the crumpled bodies that line the way. He barrels through the door, and into a nightmare.

The hall is littered with soldiers, Morgana's his mind notes absently, Not mine, not Camelot's, Morgana's. Those that still stand, a small band indeed, are involved in a vicious confrontation with Camelot knight's, the battle circling around something. The knight's cloaks billow out behind them, a lazy arc of red, and in the momentary clearings between, Arthur sees a sight that will haunt his nightmares until the day he dies, bleeding out under the sun on a battlefield that will exist many years from now.

Morgana stands, hands raised, clearly incanting, hair and dress swirling about her in a grotesque parody of dance. The sting of betrayal becomes a throbbing wound, and Arthur snarls, stepping forward without thought. He cuts down an invader without sparing him a glance, pushing forward determinedly. It's when he sees who Morgana is standing against, that he begins to lose his bearings.

Merlin's hands are raised in imitation, eyes bright gold, his mouth moving steadily. Unlike Morgana, his hair and clothes are perfectly unruffled. Now he's closer, Arthur can see the twinge of desperation on Morgana's sneering face, and it throws him back to a time when she had been so young and unsure of herself.

"Merlin, no!"

The words are out of his mouth before he can stop them, shoving forward, willing to save any semblance of family he might manage. Merlin's concentration falters, and the wind he had obviously been holding at bay screams around the room, rattling everything in its path. The fighters are stumbling, slashing wildly, throw hard from their course, and Morgana's eyes are on Arthur, shallow and pitiless.

They lock gazes, Arthur imploring and Morgana...well, Morgana is empty of everything besides the dirty taint of revenge that singes her eyelashes, and bows Arthur's back. I've killed us all, Arthur thinks, and hears a grunt of pain, high and surprised. Arthur knows the sound of all of his knight's pain, and he knows this is Gwaine's. His eyes shoot to Merlin, whose face has gone dark as thunder.

Everything dies away, the wind, the noise of battle, the very air in the room, and a terrible silence falls, broken only by the sound of Gwaine's elbow as it clatters the flagstones, followed by the rest of him. Morgana whips around to where Merlin stands, looking more terrifying than anything Arthur has ever had to face in his short time on earth.

Instantaneously, all the remaining invaders convulse, blood specking from their lips as they gurgle, bodies arcing impossibly onto their toes with dull snaps that Arthur knows is the sound of their bones breaking inside their skin.

They fall to the ground as one, finally still, and Morgana's voice screams panic as she tries to conjure up something to save herself. Merlin's eyes haven't left the spot where Gwaine lies and he raises an arm, almost lazily, deflecting Morgana's surge of magic, lifting her writhing body into the air and sending her into the wall with a flick of his wrist. Arthur sees her broken neck in the way her head tilts backwards, puppet-like.

Merlin is at Gwaine's side immediately, hands that wrought such devastation cradling his lolling head gently, parting the chainmail like butter, searching down his flank for the wound they all know is there. His fingers come away wet with blood, and Arthur is startled by the harsh sob that rattles from the man's chest.

Arthur, emboldened by the knight's, creeps closer. Gwaine's mouth is ringed in red, and Arthur has seen enough battles to know this is the end for his incorrigible friend. He kneels by the knight's other side, taking his hand and gripping gently. Gwaine turns his face to him, and tries to smile. Arthur feels horror crawl along his bones at the bloody teeth Gwaine presents.

Gwaine turns back to Merlin. Merlin, who is...crying quietly and openly, Percival's big hand steady on his shoulder. Gwaine is trying to shush him, but Merlin is mumbling desperately, the wretched tone of his low voice tearing jagged shards into Arthur's heart.

"There must be something...something I can...this isn't...it's not your time...I can't..." Merlin's whole body is heaving with the necessity of breath, almost as if he's trying to breathe enough for the both of them, but Gwaine is shaking his head. Or trying to.

"Merlin," he gasps, his lungs already wet with fluid, "stop."

The word is barely a whisper, but it has the effect of the loudest gong. Merlin stills, his mouth shuttering uselessly. Abruptly, he leans down and presses his forehead to Gwaine's, and Arthur can see his tears hitting Gwaine's skin and rolling off uselessly.

Arthur's chest feels like it's being crushed, and he's not sure if he can watch another good man die. He's aware that some of his pain is due to Merlin's words, due to something a lot like jealousy, but that is a consideration for another day. Not here. Not now.

Gwaine dies breathing Merlin's name in his last exhalation, and his hand falls limp in Arthur's grip. Merlin goes deathly quiet, before making a noise that Arthur prays he never hears again, from him or any other living creature, and claws desperately at Gwaine's prone form. Percival pulls him away, the task much harder than it should be for a man his size, and Merlin collapses against the knight's chest, cradled there protectively.

"Take him to my chambers," he instructs Percival, before leaning close to Merlin and whispering fiercely, "If you are not there when I return, I will make you regret it." Percival gives him a disapproving glance, but ushers Merlin away as ordered.

Arthur kneels by Gwaine's motionless form, and allows himself a moment to drown in his grief. For all his faults, Gwaine was a good man, a good knight, and a loyal friend. When he is done, Leon and Elyan move to his side, lifting Gwaine's body reverentially and removing it from the wrecked room.

Arthur spends the next few hours cataloguing the damage sustained to the castle and to his people from Helios' army. He does his best to fortify defences in case anyone takes it upon themselves to see Camelot as an easy target, and by the time he makes his way back to his chambers, he has also made sure that everyone has somewhere safe to bed for the night. Tomorrow they would look to begin repairs. For tonight, they have done enough.

In his chambers, Merlin stands by the window, staring unseeingly into the darkness beyond Camelot's walls. Percival is stationed by Arthur's desk, worried eyes on Merlin's rigid shoulders.

"He hasn't moved in hours, sire," he murmurs quietly, and Arthur nods, dismissing him gently. Percival gives Merlin one last sad look and leaves, closing the door quietly behind him. Now it's just Arthur, Merlin and the weight of betrayal and grief between them.

"Were you in league with her?"

Arthur closes his eyes stupidly. That wasn't what he had meant to say. He'd opened his mouth and Uther had spilled out. When he opens his eyes again, Merlin is staring at him, dismay and resignation warring for dominance in his expression. Arthur waits, the lump in his throat making words impossible.

"I have murdered in your name, Arthur Pendragon," Merlin rasps, voice rough from tears and sorrow, "and you dare to accuse me..." He trails off, and his face shutters so suddenly that Arthur blanches. Merlin pulls himself up straight, although Arthur can see how much it is costing him in the tension vibrating in his spine, and faces him head on.

"I have lived in fear since I met you," Merlin says, voice dead of emotion, "Fear of being discovered, fear of being outed, fear of failing to keep you safe. I have given my entire life to your protection, and today I lost my closest friend through fear you would think less of me when you found out my secret." Merlin looks at Arthur, and the distance in his eyes is a terrible thing. "You take everything sire, in the end. It all comes down to you."

Arthur is speechless, angry and anguished and inexplicably hurt. Merlin stares calmly ahead, like a puppet, like nothing, and Arthur feels the first spiral of tangible fear swirl around his heart. He steps forward and curls his arm around Merlin's bicep. The flesh is firm under his hand, pulsing with life, and Arthur feels the aching wrench of a fallen brother right down to his marrow.

"Arthur?"

Merlin's voice is soft, the way it used to be when he was worried, before all of this, before... Arthur gasps, shuddering with loss, and Merlin's hands are on his shoulders, fingers fluttering against the muscle of Arthur's back, his mouth shushing against Arthur's ringing ears.

"You are a sorcerer," he huffs out, and Merlin nods once, beginning to close off again, but Arthur digs his fingers into Merlin's arms until the skin bleaches white, keeping him there. "I'm angry Merlin," he rushes, voice hot with it all, "so angry with you, so hurt but..." Merlin stops struggling against his grip at that, and in return Arthur eases the pressure on Merlin's arms. Merlin's mouth is open, his breath panting lightly against Arthur's face, and Arthur pulls him into his arms and grips desperately.

"You're all I have," Arthur says into Merlin's hair, voice frantic with it, "The closest to family I have left, Merlin. I need you to be loyal to me, Merlin. Please."

Arthur can feel the raw despair in his voice, knows the pleading Merlin must see in his eyes, but he can't bring himself to care. He has lost so much this day; a loyal knight and friend, a sister he hadn't known about until it was too late (and Gods, wouldn't he hold guilt for that forevermore?), an uncle who was blood on his beloved mother's side. He couldn't lose his most trusted friend as well, he wouldn't. He knows Merlin saw Gwaine as his closest confidante, but Merlin has always been it all for Arthur, servant, advisor, conscience, and one day Arthur would earn the same from Merlin, he was sure of it.

Merlin's hands are tender in Arthur's hair, sweeping away his anxiety. When Arthur is sufficiently gentled, Merlin looks him straight in the eye and says, "Arthur, you are, and always will be, my King. The only King I will ever serve. Our lives were entwined from the day of my birth, and I will know no other. I am a loyal subject of King Arthur of Camelot, and I am a loyal friend, protector, adviser and armour-polisher to Arthur Pendragon, the bravest man I have ever met."

Arthur's eyes are wet, the ghost of a smile on his lips, but Merlin isn't finished. "We have a destiny, you and I. You will be the greatest King who will ever live, the King of all Albion, and I will stand at your shoulder for as long as you'll let me." When he's finished speaking, Merlin drops to his knees and bows his head, awaiting Arthur's judgement.

Arthur can admit, deep within himself, that the only time he has ever felt truly himself, truly at peace, is with Merlin by his side, and he does not hesitate to lay his hands on Merlin's shoulders. Merlin tilts his face up, tears shimmering against his cheekbones, and Arthur hauls him upright and into an embrace.

There is time enough for anger and recriminations, for finding a new equilibrium in their tentative future together. Tonight, they will mourn the loss of Sir Gwaine, knight of Camelot, the most foolhardy and courageous man Arthur has known. The new realm they will build together will be a poorer place for his absence.